Method for applying flock to a resin coated substrate



Sept. 22, 1970 a KAPI5AS ETAL 3,529,986

mmaon FOR APPLYING FLOCK TO A RESIN COATED SUBSTRATE Filed April 18, 1966 GEORGE KAPPAS A. B. Z! MMERMAN INVENTOR.

Q BY QMMOK.

United States Patent 3,529,986 METHOD FOR APPLYING FLOCK TO A RESIN COATED SUBSTRATE George Kappas, Champaign, and Alfred B. Zimmerman,

Tuscola, llll., assignors to National Distillers and Chemical Corporation, New York, N.Y., a corporation of Virginia Filed Apr. 18, 1966, Ser. No. 543,332 Int. Cl. B44c 1/08; B44d N44 US. Cl. 117-17 9 Claims ABSTRACT OF THE DISCLOSURE This invention relates to textiles, and more particularly to a method of preparing flocked products suitable for many purposes.

A variety of methods have been proposed for manufacturing carpet and other textiles in which flocked material is incorporated. Flock is a cut short fiber, such as wool, cotton, or man-made materials, such as nylon,

rayon, or combinations thereof, which has been used for a great number of years for coating wallpaper, weighting fabrics, or as a stuffing for furniture. Flocked paper has been produced by first applying an adhesive to a suitable substrate and then applying the flock while vibrating or beating the substrate. The excess flock is removed after the adhesive has been allowed to dry or cure.

In conventional flocking processes for producing carpets and the like, the adhesive material, such as latex, is first applied to a suitable substrate, such as jute or burlap. Subsequently the flock is applied in such a way that it adheres to the adhesive material and provides a surface for the finished carpet or other textile.

Several techniques have been followed for the application of the flock to the substrate. One of these techniques is the electrostatic process which is particularly adapted to making items such as carpets and upholstery where high density and vertical orientation of fibers are required. By this technique, the charged flock is ejected from a hopper into an electrostatic field which directs the fiber onto the adhesive-coated substrate.

Another technique, which may be used alone or in conjunction with the above-noted electrostatic technique, is one that utilizes beater bars. These rotating bars strike the back of the substrate so as to increase the penetration of the short fibers into the adhesive as well as to knock olf loose flock. The excess flock which still remains loosely embedded is then removed, for example, by using a vacuum.

Accordingly, the primary object of the present invention is to provide an improved technique for producing flocked products, particularly carpets.

It has now been discovered that polyolefins can be used as the adhesive for flocked products, such as carpets, to provide superior moldability. Such moldability is of fundamental importance in the production of carpets for automobiles since these carpets must be capable of being readily fitted to desired contours. The use of polyolefins Patented Sept. 22, 1970 as the adhesive for retaining the flock provides a carpet having excellent fiber bond and pillingand abrasionresistance properties. Other advantages are that the carpet has dimensional stability and freedom from odor. Further, the carpet can be readily cleaned or shampooed, it has resistance to moisture and mildew, and it possesses color stability. Additionally, there is no danger during fabrication from the use of flammable solvents.

The present invention in its broadest aspect provides a technique of incorporating flock into a substrate so that the finished article will have the appearance and texture of a tufted product. More specifically, the technique of the present invention comprises applying a thermoplastic organic polymer, such as polyethylene, to a substrate so that flocked material may adhere thereto. In the instance of the use of polyethylene, one form of same is a normally solid homopolymer as described in Fawcett, US. Pat. No. 2,153,553. Such a polymer is a tough solid at normal temperatures with a fusion point of above about 250 F., corresponding in composition substantially to (CH and showing a crystalline structure by X-ray diffraction. Typically it has a molecular weight in excess of about 10,000. Other polymers can also be used, for example, foamable polyethylene, ethylene-vinyl acetate copolymers, and ethylene-methyl acrylate copolymers.

It should be pointed out that the foregoing materials constitute percent solids systems which result in great economic advantages with respect to application speeds. That is to say, these systems involve much greater speeds than processes based on conventional solvents or aqueous adhesives. In fact a continuous process is made possible by virtue of the materials that are used. Such a continuous process produces flocked products at greater speeds and with greater safety than can be obtained with conventional adhesives.

In accordance with the basic technique of the present invention, a variety of application methods may be utilized in applying the adhesive carrier to the substrate. One preferred form of the technique involves the application of the polyolefin, such as polyethylene, as a powder onto a surface of the substrate. In another embodiment of the technique, molten polyolefin is extruded onto the substrate. This latter method, however, is particularly adapted for use with higher molecular weight polyolefins.

In the preferred embodiment of the technique of the present invention, the polyethylene, having been applied in powder form to a surface of the substrate as noted above is subjected to infrared or other heating whereby the powdered polyethylene melts to form a continuous superstratum. Thereafter, the web, constituted of the substrate with the applied superstratum or layer of polyethylene, is passed between rolls to smooth out the polyethylene. Subsequently, the web is heated to melt the polyethylene. The flock is then applied to the molten polyethylene and adheres thereto. A series of mechanical heaters is used at a subsequent stage to insure adequate penetration by the flock and to remove any excess flock that has not adhered.

The foregoing and other objects, features, and ad vantages of the invention will be apparent from the following more particular description. of preferred embodiments of the invention.

The figure is a schematic representation of apparatus suitable for carrying out one embodiment of the technique of the present invention.

Referring to the figure, there is shown a complete layout for fabricating the flocked carpet or the like. A series of stations 1, 2, 3, 4, 5 and 6 are illustrated. At these diiferent stations, one or more operations are per formed in forming the flocked product according to the instant technique. Shown in this figure is a typical carrier member in the form of a continuous belt 7. Belt 7 is moved in the direction shown by the arrow by means of a take-up roller 8. Subsequently, belt 7 passes a series of additional rolls 9, 10 and 11.

The substrate 12, is fed from a roll 13 onto the continuous belt 7 and moves therewith past the rolls 9, 10, and 11.

At station 1 which includes a feed hopper 14, a source of heat 15, and a pair of rolls 17 and 18 the polyolefin 16 which is contained in the feed hopper 14 is fed onto the substrate 12. The substrate 12 passes through the heating tunnel or oven 15 containing a source of infrared radiation.

Application of heat causes the polyolefin powdered form to melt, and the coating 16 thus formed is smoothed out by means of the rolls 17 and 18. A temperature within the range of about 300 to 500 F. is generally used.

The continuous layer 16 of adhesive thus formed is subjected to a heating step at station 2 prior to the flocking operation. Thus the polymer surface becomes molten, resulting from the application of heat by sources 19 at a temperature of about 300 to 500 F. In the next step of the operation, at station 3 electrostatic flocking is carried out. Such a technique is important in obtaining high density and vertical orientation of the short fibers. At this station 3 an electrostatic flocking unit 20 provides an electrostatic field which directs the flock from a hopper onto the polyolefin coating. The web of the substrate and the polymer coating 16 moves continuously at 90 to the fields force lines. Thus the fibers align with the field and strike end-on at 90 to the web. A charged screen in the hopper (not shown) forms a positive pole, and a grounded plate over which web passes forms a negative pole. Most of the fibers thus directed adhere to the molten surface of the polymer coating, but some of them do not imbed in the polymer adhesive. Such excess is later removed.

At the station 4 mechanical beaters in the unit 21 carry out the next step in the process. These beaters are in the form of rotating bars which strike the back of the web and are used to increase the penetration of the flock into the polymer coating as well as to knock off loose flock.

In some instances another heating step is used after the application of the flock to the substrate. Depending upon the nature of the flock, the heating step is carried out for about 5 to 10 minutes at about 300 to 400 F. to allow the fiber and polymer to form a bond. This post-heating step is performed at station 5 by means of heat source 22. The excess fiber is removed after the web has been cooled, although some of the excess fiber as noted above can be recovered in the beater bar unit. The final fiber recovery cannot be made until the polymer has been cooled, a brushing action being required in this final fiber recovery which would damage the flocked material while it was still hot.

Immediately after the post-heating step, or concurrently therewith, the web constituted of the substrate, the polymer layer, and the flock, is separated from the continuous belt 7. It is brought over a chilled roll 23 as illustrated and then finally over the roll 24 and past station 6 at which a vacuum is applied by unit 25 to remove the excess fiber as noted above. The finished web is then taken off the auxiliary roll 24. The temperature that has been found suitable for cooling down the web at the chilled roll 23 is approximately 100 F.

The description of our preferred process includes a combination of electrostatic and mechanical means for applying flock to the coating. It will be understood, however, that either method can be used alone and that any other suitable means of applying the flock is within the scope of this invention.

Although the polymer referred to in the above description of the preferred technique is polyethylene, it will be understood that other olefin homopolymers and copolymers, e.g., of ethylene and other monomers, such as ethyl acrylate, methyl acrylate, and vinyl acetate are suitable.

While this invention has been described with regard to applying the polyolefin as a powder, it is also possible to apply the polyolefin in other forms, e.g., as a preformed sheet, by extrusion coating, or by curtain coating.

The melt index of the selected polymer has an influence on the adhesion of the flock to the polymer. Higher melt index polyethylene has been found to perform better in this system than low melt index polyethylene. This is due to two factors: (1) The higher melt index resin offers less resistance to fiber penetration and (2) the higher melt index resin has a longer open tack time, the surface of the resin being receptive to the fiber for a longer period of time after the heat source has been removed.

In general ethylene-vinyl acetate copolymers have been found well-suited to flocking applications in accordance with the broad technique of the present invention. For some applications these copolymers are better suited than polyethylene. The ethylene-vinyl acetate copolymers have better adhesive properties than the homopolymers of ethylene, and this is particularly important for intermediate and long fiber flock. For very short flock applications, ethylene homopolymers are as well suited as the copolymers.

The following specific examples are given to aid in understanding the present invention, but it is to be understood that the invention is not restricted to these specific compositions or to the conditions of application given in the examples. All proportions throughout these examples are by weight unless otherwise noted.

EXAMPLE I (A) parts of 16-mesh ethylene-vinyl acetate copolymer powder having a molecular weight greater than 20,000 was applied to burlap at a coating weight of 15 ounces per square yard. The burlap was heated under a high intensity infrared heater for one minute to melt the powder. The burlap was removed from the oven and nipped using a hand roller with moderate pressure to smooth and solidify the coating. The coated burlap, attached to a cardboard support, was placed in a laboratory hot-air circulating oven for ten minutes at 350 F.

During the heating cycle 4-mm., 30-denier nylon flock was placed in the Spellman Laboratory Model 60PN High Voltage Flocking Machine. After the heating cycle, the coated burlap (on the cardboard support) was placed upside down over the pan containing the nylon flock as quickly as possible so as not to excessively cool the ethylene copolymer coating. A metal plate was placed on top of the cardboard containing the coated burlap. The beamer was placed on the metal plate and the voltage was brought to 50 kilovolts. The flock was attracted to the metal plate and adhered to the molten copolymer.

The voltage was reduced to zero, and the burlap was placed in the 350 F. oven for seven minutes to achieve optimum adhesion of the flock to the polyolefin.

(B) The above process could be made continuous. In that case the post-heating step probably would not be necessary since the flock step would be accomplished rapidly enough so as not to cool significantly the polyolefin surface.

EXAMPLE II 100 parts of 16-mesh ethylene-vinyl acetate copolymer powder having a molecular weight greater than 10,000 was metered onto cotton fabric at a coating weight of 20 ounces per square yard. The fabric was placed in a laboratory hot-air circulating oven for ten minutes at 350 F. The fabric was then removed from the oven and nipped using a handroller with moderate pressure to smooth and solidify the coating. The coated fabric was attached to a cardboard support and placed back into the hot-air oven for ten minutes.

During this heating cycle 4-mrn., 53-denier nylon flock was placed on a -mesh screen used as the flock feeder. The six-sided beater bar was turned on at 1725 rpm. The coated fabric was removed from the oven. The screen feeder containing the flock was placed on top of the molten polyolefin copolymer adhered to the fabric. The cardboard support was tightly held and moved in a circular motion on the beater bar. The vibration of the beater bar caused the flock to fall through the screen feeder and adhere to the molten copolymer.

The fabric was placed in the 350 F. oven for seven minutes to achieve optimum adhesion of the flock to the polyolefin.

EXAMPLE III 100 parts of a polyethylene homopolymer having a molecular weight greater than 20,000 (SO-mesh, 2.0 melt index, 0.917 density) was metered onto burlap at a coating weight of 8 ounces per square yard. The burlap was then placed in a laboratory hot-air circulating oven for ten minutes at 350 F. The burlap was then removed from the oven and nipped using a hand roller with moderate pressure to smooth and solidify the coating. The coated burlap was then attached to a cardboard support and placed into the hot-air oven for ten minutes.

During this heating cycle 1-mm., 3-denier nylon flock was placed on a 20-mesh screen used as the flock feeder. The six-sided beater bar was turned on at 1725 rpm. The coated burlap was removed from the oven. The screen feeder containing the flock was placed on top of the molten polyethylene adhered to the burlap. The cardboard support was tightly held and moved in a circular motion on the beater bar. The vibration of the beater bar caused the flock to fall through the screen feeder and adhere to the molten polyethylene.

The fabric was placed in the 350 F. oven for seven minutes to achieve optimum adhesion of the flock to the polyethylene.

What is claimed is:

11. A process of producing a flocked product comprising the steps of (a) applying a powder of a 100% solid system of a resin from the group consisting of polyethylene and ethylene vinyl acetate copolymer to a substrate on a support,

(b) heating the resin powder on said substrate at a temperature required to melt said resin to form a continuous resin supcrstratum on said substrate,

(c) smoothing out the surface of said continuous resin supcrstratum after said heating,

(d) heating said continuous resin superstratum after smoothing but prior to flocking to a temperature suflicient to melt said resin,

(e) directing flock normal to the path of movement of said substrate to impart a vertical orientation to said flock with respect to said substrate, whereby the bulk of said flock is directly embedded into the molten surface of said resin layer, said resin layer being in the form of a continuous superstratum,

(f) subjecting the flocked material to an impacting from the rear of the substrate with mechanical beater bars, whereby the flock is further penetrated into said resin superstratum and excess nonadhering flock is removed,

(g) heating the impacted flocked material, whereby said resin and said flock are firmly bonded,

(h) cooling the flocked substrate after said resin and said flock are firmly bonded,

(i) removing the excess flock after cooling, and

(j) stripping the flocked substrate from said support.

2. The process of claim 1 wherein the polyolefin is polyethylene having a molecular weight greater than about 10,000.

3. The process of claim 1 wherein said substrate heating of step (d) is performed at a temperature within the range of from about 300 to about 500 F.

4. The process of claim 1 wherein said heating of step (g) is to a temperature within the range of from about 300 to about 400 F.

5. The process of claim 4 wherein said heating is conducted for a period of from about 5 to about 10 minutes.

6. The process of claim 1 wherein said polyolefin is applied to said substrate while said substrate is moving.

7. The process of claim 1 wherein said flock is directly embedded into the molten surface of said polyolefin layer from a point above said substrate.

8. The process of claim 1 wherein said flock is directed normal to the path of movement of said substrate and directly embedded into the molten surface of said polyolefin layer by subjecting said flock to an electrostatic field, whereby said fibers are aligned with said field.

9. The process of claim 8 wherein said flock is subjected to said electrostatic field and directly embedded into said molten polyolefin layer from a point above said substrate.

References Cited UNITED STATES PATENTS 2,222,539 11/1940 Meston 117-17 X 2,303,202 11/1942 Paris et a1. 117-20 2,328,904 9/1943 Hiers 117-33 X 2,527,501 10/1950 Saks 117-33 2,639,808 5/1953 Barry et a1. 117-138.8 X 2,655,895 10/1953 Abeles 117-20 X 2,696,445 12/ 1954 Schwartz et al 117-20 X 2,963,746 12/1960 Webb et a1. 264-126 2,784,630 3/1957 Koprow et al. 161-64 2,963,381 12/ 1960 Leirnbacher 161-64 3,252,732 5/1966 Squier 161-64 X 3,275,487 9/1966 Lemelson 161-64 3,342,902 9/1967 Peterkin 117-122 X 3,356,521 12/1967 Boltniew 117-33 3,366,503 1/1968 Dillhoefer et a1. 117-17 WILLIAM D. MARTIN, Primary Examiner P. F. ATTAGUILE, Assistant Examiner U.S. Cl. X.R. 

